1. Field of the Invention
The present invention relates to a video apparatus, and more particularly, to a video apparatus having a display module and a method of controlling a power supply mode of the display module, in which an automatic gain control (AGC) value is obtained based on the signal strength of a received broadcast signal.
2. Discussion of the Related Art
A video apparatus receives a signal, which typically includes separable audio and video signals, from a specific source, e.g., a broadcast channel, and extracts the video signal from the received signal. The video signal is then separately processed for display on a display module such as a cathode ray tube, liquid crystal display, or plasma display panel (PDP) module. The PDP module, which is being increasingly adopted as the display module for application in consumer televisions, has a basic structure enabling the fabrication of a much thinner device than a video apparatus employing a cathode ray tube and exhibits better luminance characteristics than a video apparatus employing a liquid crystal display.
Referring to FIG. 1, in addition to a PDP module, a contemporary video apparatus comprises a tuner 110 for selecting (tuning) a specific broadcast signal from among a plurality of broadcast signals received via an antenna or input means; a demultiplexer 120 for separating the specific broadcast signal as received into its component signals, including at least a video signal and typically including an audio signal and related channel information; a video processor 130 for processing the video signal to be displayed on the PDP module 140; and a controller 150 for controlling the respective blocks according to input commands, which include at least an input for broadcast channel selection, typically made by a user.
In the operation of the above video apparatus, with the device powered to enable a broadcast channel selection, either by a default condition or by a specific user input, the controller 150 outputs to the tuner 110 a control signal for tuning the specified broadcast channel, and in doing so, the tuner selects and outputs a received broadcast signal of the frequency of a specified channel. The selected broadcast signal of the specified channel is input to the demultiplexer 120 to be separated into a video signal, an audio signal, and additional information. If the specified channel contains a video signal, the demultiplexer 120 outputs the video signal to the video processor 130, which processes the received video signal to enable its display on the PDP module 140.
In practice, however, the strength of the electric field of the received video signal, i.e., the input signal strength, may abruptly vary over time, particularly in a hysteresis region relative to the varying strength, such that a power supply mode for driving the PDP module is subject to excessively frequent changes, in which case an internal temperature of the video apparatus may also exceed acceptable limits. Unduly high internal temperatures may also result if, for a particular channel, a received video signal has a weak electric field strength or there is no signal input, while viewing of the broadcast signal of the channel continues. In particular, a television tends to become overheated in the presence of the input of a weak RF signal or one exhibiting a high level of white noise. To overcome such an overheating phenomenon, contemporary video apparatuses, particularly those utilizing PDP modules, employ heat-sinking techniques for the PDP module and special components that are resistant to high temperature conditions, to accommodate a larger margin of heating tolerance, which leads to substantially increased product costs.